I am preparing a darks library for SHO. I took an educated guess based on previous experience with Hydrogen Alpha that an exposure of 50 seconds, unity gain of 389, and offset of 30 is ideal. Well, maybe not "ideal" but I will get a stackable print without saturating stars.

A demonstration of what happens when 9am darks are applied to 9pm lights and vice versa would be very educational. An extreme test but should be a good demonstration about why to avoid temperature mismatches.

This is indeed really very interesting. I just wanted to share a different thought to add here, not in anyway trying to take away from your approach though.

I can't help but thinking that when I faced this issue with mismatched temperatures in dark subtraction with my DSLR, I always adopted the LENR function to automatically take a single dark to be subtracted from the preceding light, this of course at the expense of half my skytime, but it worked surpisingly well (there are of course arguments for master dark subtraction beeing better than single dark frame subtraction).

When I use to do this, it was an effort to avoid the problem you illustrate above as much as possible. I think this could be another way to be able to apply such an approach to uncooled CMOS cameras, for the camera to either have a mechanical shutter, which it obviousky doesn't and probably never will, or connected to a filter wheel with a dark frame filter. Of course, you'd need still need a script or some function that doesn't exist yet, which would mimick the function carried out by DSLR LENR - take a light then immediately after a dark frame, then subtract it from the light and render a single dark subtracted single light frame to work with.